The present invention relates to a method of DNA transfer between cells, resulting in protein expression in the recipient cell. Further, the invention also relates to the use of such DNA transfer in a method of treating and/or preventing clinical conditions.
Cell death in multicellular organisms is known to follow one of two pathways, namely necrosis or apoptosis. Necrosis is known to be the pathological form of cell death, and usually the result of physical injury, while apoptosis is genetically controlled and the deliberate cellular response to specific environmental and developmental stimuli. Apoptotic cell death is characterized by plasma blebbing, cell volume loss, nuclear condensation, DNA fragmentation and the generation of membrane enclosed apoptotic bodies. These apoptotic bodies are rapidly removed by phagocytosis of neighboring cells. The recognition of apoptotic bodies by macrophages, dendritic or neighboring cells is mediated by several different pathways. Surface receptors such as the vitronectin receptor (avxcex23) and thrombospondin receptor (CD36) located on the macrophages may recognize apoptotic cells via the binding of thrombospondin (Savill J, Fadok V, Henson P, Haslett C: Phagocyte recognition of cells undergoing apoptosis. Immunol Today 14:131, 1993). Translocation of phosphatidylserine from the inner to outer side of the cell membrane serves as recognition signals for phagocytosis. Not only macrophages are capable of phagocytosing apoptotic bodies. Injection of apoptotic liver cells in the portal vein in the mouse liver results in uptake of apoptotic bodies in the liver endothelial cells. In vitro, apoptotic macrophages are rapidly phagocytosed by human fibroblast cells within 1 h.
Since it has now been shown that apoptosis plays an essential role not only in the embryonic development, as previously thought, but also occurs normally in healthy adult individuals, the latter has attracted a great interest during the past decades. More specifically, it has been shown that apoptosis is involved in a large number of wide spread diseases, such as infections, cancer and autoimmune diseases.
Thus, the control of cell number in multicellular organisms depends on the fine balance between cell proliferation and cell death. As mentioned above, cell death by apoptosis plays a key role in the elimination of cells during embryonic development as well as in adults. It is for example involved in the negative selection of neural cells, removing redundant cells during organ formation. In adults, apoptosis plays an important role in the maintenance of tissue homeostasis. Apoptosis is also of importance in tumor development. It may serve as an anticancer mechanism by restricting the expansion of cells with unleashed proliferative potential.
Thus, since too much or too little apoptosis is believed to play a role in the most common diseases, research is directed to find new forms of treatment based on a more thorough understanding thereof. A much desired goal would be to understand the mechanism behind as well as consequenses of apoptosis well enough to enable control of such disorders.
Accordingly, one object of the present invention is to provide a method of DNA transfer by the uptake and reuse of apoptotic bodies by somatic cells. A specific object is to provide a method of preventing and/or treating a clinical condition in a patient, which in an advantageous embodiment enables use of an antigen derived from the said patient as a therapeutical vaccine. Accordingly, the present invention also encompasses a process for the manufacture of a pharmaceutical composition, which composition can be specifically designed for each patient to be treated. Thus, yet another object of the present invention is such a personalized, therapeutic vaccine. The different objects are achieved as detailed in the appended claims.